Process of treating kaolin for the production of carborundum and alumina.



' PATENTED MAY 19,1903.

v BMW? I'. C. WEBER.

No*I 728,528.

PROCESS OFTREATING KAOLIN FORTHE PRODUCTION OP CARBO'RUN'DUM ANDALUMINA. APPLIGATION .FILED Nov. s, 1902. lo 101m..

FREDERICK .of WEBER,

Patented May 19, 1903.Y

lPATENT OFFICE.

OF CHICAGO, ILLINOIS.

PROCESS OF TREATING KAOLIN FOR THE PRODUCTION OF CARBORUNDUM ANDALUMINA.

SPECIFICATION forming part of Letters Patent No. 728,528, dated May 19,1903. Application filed November 3, 1902. Serial No. 129,999. (Nospecimens.)

To all whom it may con/cern;

Be it known that I, FREDERICK C. WEBER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and usel ful Improvement in Methods or Processesof Treating Kaolinor Fire-Clay for the Produc` tion of CrystallineOarbor'undum and Amorphous Alumina, of which the following is aspecification. l

The only known source of crude material which can be utilized in theproduction of metallic aluminium is kaolin in unlimited quantities orfire-clay, and in order toattain the result of making metallic aluminiumfrom the material named such material must 4be sep-.

arated for the alumina to 'be free from the silica which is chemicallycombined with the alumina, and by this is meant not only that the kaolinor fire-clay must be dissociated, separating the alumina from thesilica, but such separation must be of a nature and in such manner as toleave a pure alu mina-that is, alumina free from water, iron, silica,and

other im purities-so that the produced'inetaL.

lic aluminium shall be a metal as pure as the metal made from themineral bauxite.

The present invention has for its object the attainment in a practicaland successful manner of the conversion of kaolin into the condition ofcrystalline carborundum and amorphous alumina, for further treatment ofthe amorphous alumina and Ythe production of pure metallic aluminiumrandthe invention consists in the method or process and Ithe va-V rioussteps thereof hereinafter described, and pointed out in the claims. Y

In carrying out the method or process o f the present invention kaolinhaving the chemical formula Al2O3-]2SiO2-}2H2O is charged into asuitable furnace, preferably a reverberatory furnace, and roastedtherein toan.

of the furnace. The produced clinker of anhydrous aluminium silicate isremoved from the furnace and ground in a suitable mill or otherwisecomminuted, so as to be inthe condition of a coarse powder. A millsuitable forthe grinding can be a Cornish type of mills for grindingpurposes having rolls of different degrees of hardness, one roll beingof nickel-steel hard and tough and the other roll of carbon-steeltempered to be softer, by

,which formation of rolls the acting faces of the rolls become rough'anduneven, and such roughness and unevenness operates to catch and biteitheclinkers and effectually breaks and grinds the material into thecondition required, it being understood that for powdered or finematerial after thegrinding a sifter of any suitable construction is tobe used for separating the finely granulated or powdered material fromlthe coarser. The coarsely-powered anhydrous aluminium silicate is thenmixed with coarsely-powdered coke in atomic proportions to produce whenthe mixture is passed through an electric arc or is subjected to thetemperature ot' the electric arc molecular changes and productsconsisting of ture of coarsely-powdered anhydrous alumini- VumV silicateand coarsely-powdered coke in atomic proportions to the temperature ofthe electric arc heats the'material of the charge to that degree whichis required to'dissociate the anhydrous aluminiumsilicate molecules andyfurnish nascent atoms of aluminium, silicon,

andoxygen, which elements at the tempera- `ture' ofthe electric arc (therequired amount of caloric being present) rearrange themselves to formthe new molecules silicon carbid and aluminium carbid and carbonmonoxid.This resultant action from subjecting the charge of, material to theaction of the electric arc 4arises from the fact, which enablesthis'step of the process to be carried ont, that the tem-l perature atwhich silicon carbid and the temperature at which aluminiumoarbid are'each produced is so near together that the two resultants can be madetogether in an electric furnace and in this manner and by this meansprovide for their separation as usual in chem- Vical operations byforming methane in the further treatment or steps of the process.

The resulting solid mass of aluminium carbid and silicon carbid aft-ertreatment by the electric arc is removed and thrown into a tankcontaining water, where a chemical change takes place and the aluminiumcarbid is decomposed according tothe following equation:

A14034-12H20zscnamgonp,

forming methane and aluminium hydrate, of which the gaseous methane isallowed to go to waste, leaving the aluminium as a hydrate. This actionresults in separating the crystalline carborundum from the mass ofaluminium hydrate by reason of the inert-ness of the crystallinecarborundum, and the crystalline carborundum will settle to the bottomof the tank.

The resultant aluminium hydrate is separated from the crystallinecarborundum by subjecting the material to a washing and lilteringprocess by which the aluminium hydrate is washed out and the liquidcontaining the aluminium hydrate is then to 'ne evaporated to dryness,leaving the aluminium hydrate in a dried condition` and in thiscondition the aluminium hydrate is placed upon the hearth of preferablya rcverberatory furnace and subjected to a heat of 560o centigrade forthe furnace, resulting' in driving olf of all the molecular orchemically combined water and the production of anhydrous alumina (A503)or amorphous alumina, which can be subjected lo the heat of the electricarc in any usual and well-known way and then reduced in a uorid bath, asusual in producing metallic aluminium.

The various steps of the method or process of the present invention maybe stated as follows: subjecting kaolin ot' the nature stated to aroasting to drive otl the water and leave anhydrous aluminium silicate,reducing the clinker of anhydrous aluminium silicate to a coarse powder,mixing the coarsely-powdered anhydrous aluminium silica withcoarselypowdered coke in atomic proportions, subjecting the mixture ofanhydrous aluminium silicate and coke, both in a powdered condition, tothe action of an electric arc, thereby producing silicon carbid andaluminium carbid and carbon monoXid, depositing the aluminium carbid andsilicon carbid in water and forming thereby methane and aluminiumhydrate, separating the aluminium hydrate from the crystallinecarborundum by a washing process, evaporating the liquid containing thealuminium hydrate to a condition where dried aluminium hydrate onlyremains, and then subjectingthe dried aluminium hydrate to a heatsufficient to produce anhydrous alumina or amorphous alumina as the nalresultant of the process of the invention for the production of puremetallic aluminium.

The method or process of the present in vention enables the crudematerial--kaolin or fre-clay-to be successfully and practically treatedso as to produce as a resultant anhydrous alumina or amorphous aluminafor use in making pure metallic aluminium, and by the method or processof the present invention the anhydrous alumina or amorphous alumina isproduced at a cost which will allow of its use in making pure metallicaluminium without any extra treatment for the removal of iron or otherimpurities, as the anhydrous alumina or amorphous alumina from kaolinorfire-clay is free from iron and other impurities which would interferewith its being practically used for making metallic aluminium. It is tobe understood that the term coke is intended to include any suitableform of carbon.

The necessary appliances for carrying out the process of the inventionare illustrated in the drawing, in which the figure represents theseveral appliances in the order in which they are used in carrying outthe steps of the process.

A is a reverberatory furnace of any usual and well-known form ofconstruction in which kaolin is charged to be reduced to a clinker.

B is a grinding mill or rolls of the general type of what is known ortermed Cornish mills or rolls, the mill or rolls being shown essentiallyin outline. The clinkers from the reverberatory furnace are placed inthe hopper Z) and are fed therefrom between the crushing-rolls b and b2,one of which is harder than the other, as hereinbefore described.

O is an electric furnace into which the pow dered clinker after itleaves the mill or rolls and is mixed with coke is transformed intosilicon carbid, aluminium carbid, and carbon monoxid.

The furnace C has a passage or chamberc, into which the carbons c2project, so as to form an arcing space between the ends of the carbons.Through this space the powdered clinker and the coke are fed. Thepowdered clinker and the coke are deposited in a hopper C and are fedfrom the hopper through a delivery-spout c', and with the passage of thepowdered material through the arcing space of the carbons the resultantfalls into the hopper C2, from which it can be removed in any suitablemanner.

D is a tank containing wat-er, into which the resultant from theelectric furnace in the shape of a solid mass of aluminium carbid andsilicon carbid is placed for the chemical change to take place, by whichthe aluminium carbid is deposited, forming methane and aluminiumhydrate. The water, as shown, is supplied to the tank through adischargenozzle d; connected with a valve-controlled pipe cl, leadingtoa suitable source of watersupply.

E is a tank in which the resultant aluminium hydrate and the crystallinecarborundum are separated, for which purpose the tank has aIiltering-screen e, through which IOS IIO

IZO

the liquid containing the aluminium hydrate passes into the lowerportion of the tank, which liquid is subsequently to be evaporated todryness, so as to leave aluminium hydrate in a dried condition, whichaluminium hydrate is to be placed on the hearth of a reverberatoryfurnace, like the furnace A or other furnace, and subjected to heat, ashereinbefore described.

What I regard as new, and desire to secure by Letters Patent, is-- 1.The method or process of treating kaolin or fire-clay and producingcrystalline carborundum and amorphous alumina, which consists in lirstdriving O under heat both the non-combined and chemically-combined Waterfrom the kaolin, and thereby forming a clinker of anhydrous aluminiumsilicate,then

powdering the clinker and mixing the same in atomic proportions withpowdered coke and treating the powdered mixture under heat and therebyforming aluminium carbid and silicon carbid and carbon monoxid,substantially as described.

2. The 'method or process of treating kaolin or fire-clay and producingcrystalline carborundum and amorphous alumina, which consists in firstdriving off under heat both the non-combined and the chemically-combinedWater from the kaolin, and thereby forming a clinker of anhydrousaluminium silicate, then powdering the clinker and mixingV the same inatomic proportions with powdered coke and subjectingthe mixture ofpowdered anhydrous aluminium silicate and coke to the temperature of anelectric arc, and thereby forming aluminium carbid, silicon carbid andcarbon monoxid, then washing the same and forming methane and aluminahydrate and driving off under heat the molecular Water, substantially asdescribed.

3. The method or process of treating kaolin or fire-clay and producingcrystalline carborundum and amorphous alumina, which consists indissociating under heat'- the kaolin molecules, driving off the waterand forming .a clinker of anhydrous aluminium silicate,

powdering the clinker of anhydrous aluminium silicate and mixing thesame in atomic proportions with powdered coke, subjecting the mixture ofpowdered anhydrous'aluminium silicate and coke to the temperature of anelectric arc, forming silicon carbid and aluminium carbid and carbonmonoxid, treating um silicate and mixing the same in atomic vproportions with powdered coke, subjecting the mixture of powderedanhydrous aluminium silicate and coke to the temperature of an electricarc, forming silicon carbid and aluminium carbid and carbon monoxid,treating the solid mass of aluminium carbid and silicon carbid thusformed with water forming methane and aluminium hydrate, washing out thealuminium hydrate from the crystalline carborundum formed and thendrying the aluminium hydrate and forming anhydrous or amorphous alumina,substantially as described.

j 5. The process herein described of treating kaolinv or fire-clay andproducing crystalline carborundum and amorphous alumina,which consistsin forming silicon carbid and aluminium carbid from kaolin, thensubjectingv the lresultant product to the action of water formingmethane and aluminium hydrate, and then separating by washing thealuminium hydrate from the crystalline carborundum, substantially asdescribed.

6. The process herein described of treating kaolin or fire-clay andproducing crystalline carborundum and amorphous alumina, which consistsin forming silicon carbid and aluminium carbid from kaolin, thensubjecting the resultant to the action of water forming methane andaluminium hydrate, then washing and thereby separating the aluminiumhydrate from the crystalline carborundum, and then drying the aluminiumhydrate and subjecting the same to heat driving off the molecularl orchemically-combined water and forming anhydrous or amorphous alumina,substantially as described.

FREDERICK C. WEBER.

Witnesses:

OSCAR W. BOND, PAULINE BECKMAN.

